U.S. patent number 10,669,123 [Application Number 15/839,282] was granted by the patent office on 2020-06-02 for method for avoiding unwanted safety gear tripping in a safety stopping system of an elevator system, a safety stopping system, and an elevator system.
This patent grant is currently assigned to KONE CORPORATION. The grantee listed for this patent is KONE Corporation. Invention is credited to Markus Salmi, Jarkko Saloranta, Veli-Matti Virta, Timo Vlasov.
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United States Patent |
10,669,123 |
Virta , et al. |
June 2, 2020 |
Method for avoiding unwanted safety gear tripping in a safety
stopping system of an elevator system, a safety stopping system,
and an elevator system
Abstract
In an elevator system, so as to avoid unwanted safety gear
tripping, the kinetic energy, which is caused by inertia of the
overspeed governor rope to the lever arm, is dissipated by
implementing fluid viscous damping to dampen the rotary movement of
the spindle shaft to prevent unwanted safety gear tripping in the
event when the upwards movement of the moving mass is decelerated
by a machinery brake to perform a quick stop of the moving mass.
The fluid viscous damping is effected by a viscous fluid damper
which is arranged in the synchronization linkage mounted to the
moving mass.
Inventors: |
Virta; Veli-Matti (Helsinki,
FI), Vlasov; Timo (Helsinki, FI), Salmi;
Markus (Helsinki, FI), Saloranta; Jarkko
(Helsinki, FI) |
Applicant: |
Name |
City |
State |
Country |
Type |
KONE Corporation |
Helsinki |
N/A |
FI |
|
|
Assignee: |
KONE CORPORATION (Helsinki,
FI)
|
Family
ID: |
57629440 |
Appl.
No.: |
15/839,282 |
Filed: |
December 12, 2017 |
Prior Publication Data
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|
|
Document
Identifier |
Publication Date |
|
US 20180186603 A1 |
Jul 5, 2018 |
|
Foreign Application Priority Data
|
|
|
|
|
Dec 29, 2016 [EP] |
|
|
16207231 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B66B
5/18 (20130101); B66B 5/16 (20130101); B66B
5/044 (20130101) |
Current International
Class: |
B66B
5/04 (20060101); B66B 5/16 (20060101); B66B
5/18 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1840068 |
|
Oct 2007 |
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EP |
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2832139 |
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May 2003 |
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FR |
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2626408 |
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Jul 1997 |
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JP |
|
Other References
Search Report issued in European priority application 16207231,
dated Jun. 28, 2017. cited by applicant.
|
Primary Examiner: Truong; Minh
Attorney, Agent or Firm: Birch, Stewart, Kolasch &
Birch, LLP
Claims
The invention claimed is:
1. A method for avoiding unwanted safety gear tripping in a safety
stopping system of an elevator system, the safety stopping system
comprising: a machinery brake for decelerating a moving mass so as
to perform a quick stop of the moving mass; a safety gear mounted
to the moving mass; an overspeed governor; an overspeed governor
rope connected to the moving mass of the elevator system; and a
synchronization linkage mounted to the moving mass for tripping the
safety gear, the synchronization linkage comprising a lever arm
having a first end pivotally connected to the overspeed governor
rope and a second end fixedly connected to a spindle shaft to which
a safety gear tripping arm for tripping the safety gear is
connected, said method comprising the steps of: dissipating kinetic
energy caused by inertia of the overspeed governor rope to the
lever arm by implementing fluid viscous damping to dampen a rotary
movement of the spindle shaft to prevent unwanted safety gear
tripping when the upwards movement of the moving mass is
decelerated by the machinery brake to perform a quick stop of the
moving mass; and performing the fluid viscous damping by a fluid
viscous damper cylinder acting on an arm or a rod connected
directly or indirectly to the spindle shaft.
2. The method according to claim 1, wherein the damping force is a
non-linear function of velocity of a piston relative to a cylinder
of the fluid viscous damper cylinder.
3. The method according to claim 2, wherein in velocities of the
piston relative to the cylinder of the fluid viscous damper
cylinder smaller than a predetermined velocity the damping force is
arranged to increase more forcibly than in higher velocities.
4. The method according to claim 1, wherein the fluid viscous
damper cylinder is an oil damper cylinder.
5. The method according to claim 4, wherein the damping force is a
non-linear function of velocity of a piston relative to a cylinder
of the fluid viscous damper cylinder.
6. The method according to claim 1, wherein the moving mass is an
elevator car.
7. The method according to claim 1, wherein the moving mass is a
counterweight.
8. An elevator system comprising: a moving mass guided by a pair of
guide rails to be vertically movable in an elevator shaft; a
suspension rope attached to the moving mass; a traction wheel over
which the suspension rope is lead; a hoisting machine for driving
the traction wheel to move the moving mass; and the safety stopping
arrangement according to claim 7.
9. A safety stopping arrangement for an elevator system for
stopping a movement of the moving mass, the safety stopping
arrangement comprising: a machinery brake for decelerating a moving
mass so as to perform a quick stop of the moving mass; a safety
gear mounted to the moving mass; an overspeed governor; an
overspeed governor rope attached to the moving mass of the elevator
system; a synchronization linkage mounted to the moving mass for
tripping the safety gear, the synchronization linkage comprising: a
lever arm having a first end pivotally connected to the overspeed
governor rope and a second end; a spindle shaft to which the second
end of the lever arm is fixedly connected; and a safety gear
tripping arm for tripping the safety gear, the safety gear tripping
arm being fixedly connected to the spindle shaft; and a fluid
viscous damper arranged to dissipate kinetic energy caused by
inertia of the overspeed governor rope to the lever arm to dampen
the rotary movement of the spindle shaft; wherein the fluid viscous
damper is a fluid viscous damper cylinder acting on an arm or rod
connected directly or indirectly to the spindle shaft.
10. The safety stopping arrangement according to claim 9, wherein
the fluid viscous damper cylinder is an oil damper cylinder.
11. The safety stopping arrangement according to claim 9, wherein
the damping force is a non-linear function of velocity of a piston
relative to a cylinder of the fluid viscous damper cylinder.
12. The safety stopping arrangement according to claim 9, wherein
the moving mass is an elevator car.
13. The safety stopping arrangement according to claim 9, wherein
the moving mass is a counterweight.
Description
FIELD OF THE INVENTION
The present invention relates to a method for avoiding unwanted
safety gear tripping in a safety stopping system of an elevator
system, a safety stopping system, and an elevator system.
BACKGROUND OF THE INVENTION
In prior art, an elevator system comprises an elevator car which is
connected to a counterweight via suspension ropes which go over a
traction wheel driven by a hoisting machine. The elevator car and
the counterweight are both guided vertically by respective guide
rails inside a shaft. In the following, the elevator car and the
counterweight are referred to as the moving mass. The elevator
system further comprises a safety circuit having a plurality of
normally closed safety switches for monitoring the safety status of
the elevator in normal operation. If the safety of the elevator is
somehow compromised, at least one of the safety switches is opened,
the hoisting machine is deenergized and machinery brakes are
engaged so as to decelerate the moving mass for quick stop.
The elevator system further comprises an overspeed governor system
for the elevator car, which has a governor rope loop directed up
from the elevator car, over an overspeed governor pulley, then down
and under a tension weight pulley connected to a tension weight and
then up again to the elevator car to be connected to a
synchronization linkage for tripping an elevator car safety gear. A
corresponding overspeed governor system can be attached to the
counterweight.
The synchronization linkage has synchronization levers which make
the safety gear of the moving mass to engage the guide rails of the
moving mass when at least a predetermined force is applied to the
synchronization linkage by the governor rope. This predetermined
force is acting against spring forces of synchronization lever
springs such that the synchronization lever engages the safety gear
when the force applied by the governor rope exceeds the
synchronization lever spring force. The overspeed governor system
supervises the speed of the moving mass, and, if this speed exceeds
a predetermined tripping speed which is above a rated speed of the
elevator, it activates the machinery quick stop operation and,
simultaneously, decelerates the governor rope. This deceleration of
the governor rope acts against the spring forces of synchronization
lever springs such that the synchronization lever engages the
safety gear, bringing the elevator car into an emergency stop.
To summarize, a quick stop operation of the machinery is initiated
whenever the elevator safety circuit indicates a compromised safety
status of the elevator. Additionally, if the compromised safety
status is a result of an overspeed condition of the moving mass,
detected by overspeed governor, an emergency stop operation is
activated by engaging the safety gear of the moving mass.
However, in high rise elevators, the elevator travel and speed
increase such that the inertia of the governor rope increases
substantially. This brings a new challenge during elevator quick
stops carried out by the hoisting machine brakes. Namely, when the
overspeed governor rope having the increased length decelerate
during the above explained quick stop, a large force is applied to
the synchronization linkage, because the inertia of the overspeed
governor rope is large. As a result, the decelerating governor rope
is capable of producing forces to the synchronization linkage which
exceed the needed force to engage the safety gear when the moving
mass is decelerated. In other words, the safety gear might be
unwantedly engaged or tripped during quick stop although the speed
of the moving mass has not exceeded the predetermined tripping
speed for engaging the safety gear.
One solution for preventing unwanted safety gear tripping is to
increase the synchronization lever spring force. However, this has
an effect on the design of the overspeed governor since the
European lift standard EN-81-20 code requires that the tensile
force in the overspeed governor rope produced by the governor, when
tripped, shall be twice the force that is necessary to engage the
safety gear via the synchronization linkage. Stronger
synchronization leads to bigger overspeed governor rope tensile
forces and, consequently a stronger and, thus, heavier overspeed
governor rope due to required safety factor. If one wishes to
increase the force required for tripping the safety gear by
increasing the synchronization lever spring force to oppose the
inertial force of the governor rope, then, due to the EN-81-20 code
requirement, the tensile strength of the governor rope would have
to be increased which would cause the need for redesigning of the
overspeed governor system. It is evident that this will finally
lead to elevator systems in which there is no more feasible design
window for overspeed governor and safety gear system.
Prior art systems, as known from e.g. documents JP 2626408, U.S.
Pat. Nos. 7,128,189, 7,475,756 utilize springs and U.S. Pat. No.
4,083,432 utilizes a spring loaded weight for the same purpose.
OBJECTIVE OF THE INVENTION
The objective of the invention is to alleviate the disadvantages
mentioned above.
In particular, it is an objective of the present invention to
provide a simple and cost-effective measure and means for
preventing the overspeed governor rope inertia from unwantedly
engaging the safety gear.
SUMMARY OF THE INVENTION
According to a first aspect, the present invention provides a
method for avoiding unwanted safety gear tripping in a safety
stopping system of an elevator system. The safety stopping system
comprises a machinery brake for decelerating a moving mass so as to
perform a quick stop of the moving mass, a safety gear mounted to
the moving mass, an overspeed governor, an overspeed governor rope
connected to the moving mass of the elevator system, and a
synchronization linkage mounted to the moving mass for tripping the
safety gear, the synchronization linkage comprising a lever arm
having a first end pivotally connected to the overspeed governor
rope and a second end fixedly connected to a spindle shaft to which
a safety gear tripping arm for tripping the safety gear is
connected. According to the invention kinetic energy caused by
inertia of the overspeed governor rope to the lever arm is
dissipated by implementing fluid viscous damping to dampen the
rotary movement of the spindle shaft to prevent unwanted safety
gear tripping when the upwards movement of the moving mass is
decelerated by the machinery brake to perform a quick stop of the
moving mass.
The technical effect of the invention is that it prevents the
overspeed governor rope inertial forces from unwantedly engaging
the safety gear. Further, existing overspeed governor components
can be used to higher travels in high-rise elevators without
redesigning them because unintended and unwanted activation of the
safety gears does not happen in case of unplanned rapid stopping
upwards.
In an embodiment of the method, the fluid viscous damping is
performed by a fluid viscous damper acting on a member of the
synchronization linkage.
In an embodiment of the method, the fluid viscous damping is
performed by a fluid viscous damper cylinder acting on an arm or a
rod connected to the spindle shaft.
In an embodiment of the method, fluid viscous damping is performed
by an oil damper cylinder.
In an embodiment of the method, the damping force is a non-linear
function of velocity of a piston relative to a cylinder of the
fluid viscous damper cylinder.
In an embodiment of the method, in velocities of the piston
relative to the cylinder of the fluid viscous damper cylinder
smaller than a predetermined velocity the damping force is arranged
to increase more forcibly than in higher velocities.
In an embodiment of the method, the moving mass is an elevator
car.
In an embodiment of the method, the moving mass is a
counterweight.
According to a second aspect, the present invention provides a
safety stopping arrangement for an elevator system for stopping the
movement of a moving mass. T the safety stopping arrangement
comprises a machinery brake for decelerating a moving mass so as to
perform a quick stop of the moving mass, a safety gear mounted to
the moving mass, an overspeed governor, an overspeed governor rope
attached to a moving mass of the elevator system, and a
synchronization linkage mounted to the moving mass for tripping the
safety gear, the synchronization linkage comprising a lever arm
having a first end pivotally connected to the overspeed governor
rope and a second end, a spindle shaft to which the second end of
the lever arm is fixedly connected, and a safety gear tripping arm
for tripping the safety gear, the safety gear tripping arm being
fixedly connected to the spindle shaft. According to the invention
the safety stopping arrangement comprises a fluid viscous damper
arranged to dissipate kinetic energy caused by inertia of the
overspeed governor rope to the lever arm to dampen the rotary
movement of the spindle shaft.
In an embodiment of the safety stopping arrangement, the fluid
viscous damper is arranged to act on a member of the
synchronization linkage.
In an embodiment of the safety stopping arrangement, the fluid
viscous damper is a fluid viscous damper cylinder acting on an arm
or a rod connected to the spindle shaft.
In an embodiment of the safety stopping arrangement, the fluid
viscous damper is an oil damper cylinder.
In an embodiment of the safety stopping arrangement, the damping
force is a non-linear function of velocity of a piston relative to
a cylinder of the fluid viscous damper cylinder.
In an embodiment of the safety stopping arrangement, moving mass is
an elevator car.
In an embodiment of the safety stopping arrangement, moving mass is
a counterweight.
According to a third aspect, the present invention provides an
elevator system comprising a moving mass guided by a pair of guide
rails to be vertically movable in an elevator shaft, a suspension
rope attached to the moving mass, a traction wheel over which the
suspension rope is lead, a hoisting machine for driving the
traction wheel to move the moving mass. According to the invention
the elevator system comprises a safety stopping arrangement
according to the second aspect.
It is to be understood that the aspects and embodiments of the
invention described above may be used in any combination with each
other. Several of the aspects and embodiments may be combined
together to form a further embodiment of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are included to provide a further
understanding of the invention and constitute a part of this
specification, illustrate embodiments of the invention and together
with the description help to explain the principles of the
invention. In the drawings:
FIG. 1 schematically shows an elevator system according to one
embodiment of the invention,
FIG. 2 shows a detail A from FIG. 1,
FIG. 3 is an axonometric view of the safety stopping arrangement
according to one embodiment of the invention, and
FIG. 4 is a diagram showing schematically the damping force being a
non-linear function of the velocity of the piston relative to the
cylinder of the fluid viscous damper cylinder in accordance with
one embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
In the following, description will be made to embodiments of the
present invention. It is to be understood, however, that the
description is given by way of example only, and that the described
embodiments are by no means to be understood as limiting the
present invention thereto.
In particular, different exemplifying embodiments will be described
using, as an example of an elevator system to which the embodiments
may be applied, an elevator system as depicted and explained in
connection with FIGS. 1 to 3.
It is to be noted that the following examples and embodiments are
to be understood only as illustrative examples. Although the
specification may refer to "an", "one", or "some" example(s) or
embodiment(s) in several locations, this does not necessarily mean
that each such reference is related to the same example(s) or
embodiment(s), or that the feature only applies to a single example
or embodiment. Single features of different embodiments may also be
combined to provide other embodiments. Furthermore, terms like
"comprising" and "including" should be understood as not limiting
the described embodiments to consist of only those features that
have been mentioned; such examples and embodiments may also contain
features, structures, units, modules etc. that have not been
specifically mentioned.
The general elements and functions of described elevator systems,
details of which also depend on the actual type of elevator system,
are known to those skilled in the art, so that a detailed
description thereof is omitted herein. However, it is to be noted
that several additional devices and functions besides those
described below in further detail may be employed in an elevator
system.
FIG. 1 shows an elevator system and FIGS. 2 and 3 show details of
the same. The elevator system has an elevator car 2 and a
counterweight 3, which are both acting as a moving mass and are
connected to each other by suspension ropes 19. The suspension
ropes 19 are going around a traction wheel 20 which is driven by a
hoisting machine 21. A machinery brake 1 is arranged in connection
with the hoisting machine for decelerating a moving mass 2, 3 so as
to perform a quick stop of the moving mass. Because of the heavy
mass hanging on both ends of the suspension ropes 19, the
suspension ropes 19 do not slide on the traction wheel 20. When the
traction wheel 20 is driven by the hoisting machine 21 and rotates,
the elevator car 2 and the counterweight 3 move. The elevator car 2
and the counterweight 3 are guided by guide rails 16 and 17 which
are mounted to the walls of the shaft 18 in which the elevator
system 1 is provided.
FIG. 1 further shows an overspeed governor system 15 for the
elevator car 2 which comprises an overspeed governor rope 5 both
ends of which are connected to the elevator car 2 (the moving
mass). The governor rope 5 goes around a governor pulley 22 on the
top side of the elevator system and goes around a tension weight
pulley 23 connected to a tension weight 24 on the bottom side of
the elevator system. The governor rope 5 is connected to the
elevator car 2 via a lever arm 8 of a synchronization linkage 7
having tripping arms 12 for tripping a safety gear 4 against both
guide rails 16 of the elevator car 2.
FIG. 1 further shows an overspeed governor system 15 for the
counterweight 3, which is similar to that explained for the
elevator car 2. The overspeed governor system 15 for the
counterweight 3 comprises an overspeed governor rope 6 both ends of
which are connected to the counterweight 7 (the moving mass). The
overspeed governor rope 6 goes around a governor pulley 22 on the
top side of the elevator system and goes around a tension weight
pulley 23 connected to a tension weight 24 on the bottom side of
the elevator system. The governor rope 6 connected to the
counterweight 7 via a lever arm 8 of a synchronization linkage 7
having tripping arms 12 for tripping a safety gear 4 against both
guide rails of the counterweight 7.
Referring to FIGS. 2 and 3, a safety stopping arrangement has a
synchronization linkage 7 is mounted to the moving mass, such as
the elevator car 2 or counterweight 3 for tripping the safety gear
4. In this example of FIGS. 2 and 3 the synchronization linkage 7
is explained in connection with the elevator car 2, but the
counterweight 3 can be equipped with similar synchronization
linkage 7 as shown in FIG. 1. The synchronization linkage 7 is
arranged in the lower beam 25 of the sling 26 of the elevator car
2.
The synchronization linkage 7 comprises a lever arm 8. The lever
arm 8 has a first end 9 pivotally connected to the overspeed
governor rope 5. A spindle shaft 11 is rotatably bearing-mounted to
the lower beam 25. The second end 10 of the lever arm 8 is fixedly
connected to the spindle shaft 11. A safety gear tripping arm 12 is
also fixedly connected to the spindle shaft 11 so that turning of
the lever arm 8 rotates the spindle shaft and turns the safety gear
tripping arm 12. Another safety gear tripping arm 12 is arranged
(on the right side of FIGS. 2 and 3) for tripping another safety
gear 4 acting in co-operation with another guide rail 16. The
synchronization linkage 7 comprises a connecting rod 27 which
transmits the motion of the spindle shaft 11 to said another safety
gear tripping arm 12. An extension spring 28 is arranged in the
synchronization linkage 7 to oppose the tripping action. A viscous
fluid damper cylinder 13 is arranged to dissipate kinetic energy
caused by inertia of the overspeed governor rope 5 to the lever arm
8 to dampen the rotary movement of the spindle shaft 11. The fluid
viscous damper dissipates energy by pushing fluid through an
orifice, producing a damping pressure which creates a force. The
fluid viscous damper cylinder acts on an auxiliary arm 14 which is
also fixedly attached to the spindle shaft 11. In some other (not
shown embodiments) the fluid viscous damper may arranged to act on
any suitable moving member of the synchronization linkage 7, such
as arm 14 or tripping arm 12 or connecting rod 27 connected
directly or indirectly to the spindle shaft 11. In this example the
fluid viscous damper cylinder 13 compresses when the inertia of the
overspeed governor rope 5 urges the lever arm 8 to turn the spindle
shaft 11 in a clockwise direction. In some other embodiment the
fluid viscous damper cylinder 13 may be arranged to rebound in that
situation.
Preferably, the fluid viscous damper 13 is an oil damper
cylinder.
The fluid viscous damper cylinder 13 has at least two damping
ratios depending on the velocity of the fluid viscous damper
cylinder 13. The damping ratio of the fluid viscous damper cylinder
may be adjustable.
FIG. 4 shows an example of how the damping force of the fluid
viscous cylinder 13 can be arranged to vary in function of the
velocity of the piston relative to the cylinder of the fluid
viscous damper cylinder. The horizontal axis of the diagram
represents the compression (or rebound) velocity of the fluid
viscous damper cylinder. The vertical axis of the diagram
represents the damping force F. The damping force F increases as a
function of the velocity v. In the shown example, the damping force
is a non-linear function of velocity of a piston relative to a
cylinder of the fluid viscous damper cylinder. In smaller
velocities the damping force is arranged to increase more forcibly
than in higher velocities where the damping force increase is
lightened. For example, the damping force function F(v) may be
parabolic.
This ensures that the damping force will not be too high in a
normal emergency stop situation wherein the overspeed governor
system trips the safety gears, and this operation will not be
substantially delayed due to the provision of the fluid viscous
damping.
Although the invention has been the described in conjunction with a
certain type of the elevator system, it should be understood that
the invention is not limited to any certain type. While the present
inventions have been described in connection with a number of
exemplary embodiments, and implementations, the present inventions
are not so limited, but rather cover various modifications, and
equivalent arrangements, which fall within the purview of
prospective claims.
* * * * *